Keyboard controlled circuitry



1951 R. R. POWELL 2,997,703

KEYBOARD CONTROLLED CIRCUITRY Filed Aug. 3, 1956 2 Sheets-Sheet l Com uTer 68 neraTer INVENTOR, Fl Ralph RPmuen flTTORNEY.

Aug. 22, 1961 R R. POWELL 2,997,703

KEYBOARD CONTROLLED CIRCUITRY Filed Aug. 3, 1956 2 Sheets-Sheet 2 eneraTe T t 5 l 56 INVENTOR, M BY Ralph RPOuLeH Patented Aug. 22, 1961 Calif, assignor to San Gabriel, Califi, a corporation of Caii- This invention relates to keyboard controlled circuits and has particular reference to keyboard controlled circuits for coding information for use in electronic computers or the like.

As is well known, input controls for electronic computers, etc. generally comprise one or more contact closure per key, which contacts are either opened or closed upon depression of a respective key. Although such switch contacts are, in general, satisfactory, they tend to are and to cause contact chatter under other than ideal conditions. Furthermore, such keyboard contacts are subject to wear, pitting, and to dust or dirt particles being lodged between the contacts which may increase contact resistance or even cause open circuits. Also, undesirable transients and other objectional phenomena may be caused by such key controlled contacts.

Accordingly, a principal object of the present invention is to provide a keyboard circuit control devoid of make or break switch contacts.

Another object of the invention is to provide a keyboard circuit control unit of the above type capable of coding information entered on the keys.

Another object is to provide a keyboard circuit control in which the key pressure normally necessary to effect proper contact closure is obviated.

Another object is to provide a simple, inexpensive keyboard controlled circuitry having a long life.

The manner in which the above and other objects of the invention are accomplished will be readily understood on reference to the following specification when read in conjunction with the accompanying drawings, wherein:

FIG. 1 is a plan view of a ten key keyboard unit embodying a preferred form of the present invention.

FIG. 2 is a sectional elevational view taken substantially along the line 22 of FIG. 1.

FIG. 3 is a transverse sectional view taken along the line 33 of FIG. 2.

FIG. 4 is an enlarged sectional plan view illustrating one of the circuit control units and is taken along the line 4-4 of FIG. 2.

FIG. 5 is a circuit diagram illustrating the arrangement of circuit control units for effecting a binary coded input from the ten key keyboard.

FIG. 6 is a sectional elevational view through a portion of a keyboard unit illustrating a modified form of the invention.

FIG. 7 is a sectional view taken along the line 7-7 of FIG. 6.

FIG. 8 is a sectional elevational view through the keyboard illustrating another modified form of the invention.

FIG. 9 is a circuit diagram illustrating the arrangement of the circuit control devices of FIG. 8 for effecting a binary coded input from the keyboard.

FIG. 10 is a diagram of a trigger or flipflop circuit which may be used to form a pulse utilization device controlled by the ditferent circuit control units in the circuits shown in FIGS. 5 and 9.

Referring particularly to FIGS. 1 to 5, the keyboard unit illustrated therein comprises a base 11 having upstanding flanges 12 which fit within the sides of an inverted U-shaped key frame 13. A lower key guide plate 14 is suitably secured to the sides of the key frame.

A series of ten digit or amount keys 15, arranged in the usual ten key pattern, have their key stems 16 slideably supported in aligned slots formed in the frame 13 and plate 14. The keys are normally held in their upper illustrated positions by individual compression springs 17 interposed between the top of the frame 13 and the keytops of the respective keys. The tops of the various keys project through openings formed in a plastic keyboard cover 18 which is secured by screws 20 to the base 11. The screws also pass through openings in the key frame 13 to hold the same in place.

Associated with each amount key is a circuit control unit or device, generally indicated at 21. The latter comprises a substantially U-shaped metal bracket 22 secured to the base 11 by a screw 19. A permanent magnet 23 having its magnetic axis extending horizontally is secured to one leg of the bracket 22 and is located with its right hand pole face extending in close proximity to the path of the key stem 16 of the associated key. A block of plastic 24 is suitably supported by the op pcsite leg of the bracket 22 and has embedded therein four transformer cores 25 of magnetic material. These cores are toroidal in shape and are preferably formed of a material having a high degree of permeability.

The four cores 25 are located directly opposite their associated permanent magnet 23 and are located with their axes extending coincidentally with each other and at right angles to the axis of the magnet 23.

It will be noted that the cores are located in close proximity to their respective magnet 23 so that when the respective key is in its normal raised position, the magnetic flux produced by the magnet will be sufficient to magnetically saturate the associated cores.

As shown in FIG. 4, each core 25 has a primary Winding 26 and a secondary winding 27 thereon, so arranged that in the absence of saturation of the core, any suitable pulse or change in current through the primary winding will generate a pulse in the secondary winding.

Although the windings are shown as coils wound on the respective core, they may, instead, each comprise a single wire extending through the opening of the core in such relation thereto as to develop a magnetic flux in the core upon application of a current change therethrough or to develop a pulse or current change therein upon a sufficient change of flux in the core.

Since all of the cores 25 are normally magnetically saturated, any application of a pulse or change in current in the primary windings of the cores will have no effect on their secondary windings. However, upon depression of a key, its key stem 16, which is preferably formed of soft iron or similar material capable of shielding magnetic flux, will move into the dot and dash line position 16a (FIG. 2) to exert sufiicient shielding effect on the magnetic flux produced by the associated magnet 23 to prevent the associated cores from becoming saturated so that pulses may now be generated in the secondary windings of these associated cores by application of current changes in their respective primary windings.

FIG. 5 illustrates the wiring of various core windings in order to produce a binary coded representation of any decimal digit set up by depression of a correspondingly numbered amount key 15.

To facilitate illustration, the cores are schematically illustrated as inclined bars. The lines extending vertically through the cores represent the primary windings and the lines extending horizontally through the cores represent the secondary windings. Four binary lines 53, having the values 1, 2, 4 and 8, assigned thereto, are provided, these being connected in series with the secondary windings of certain of the cores and are further connected to the inputs of respective flip-flop circuits 30. The latter are represented as being included in the circuitry of a computer 31.

The primary windings are all connetced in series through a circuit 32 which is connected to a pulse generator 33 also included in the computer. In those cases where cores having low magnetic remanence properties are used, the generator 33 may generate pulses of a single polarity. Also, the various primary and secondary windings are so arranged that all pulses introduced in the binary lines 53 are of similar polarity. However, in cases where cores having high magnetic remanence properties are used, the generator should generate pulses of double polarity in order to return the cores to their original conditions after being magnetized.

It will be noted that although four cores are provided for each key for uniformity and convenience in assembly, as shown in FIG. 3, only one, two, or three cores associated with any one key are wired into the circuit of FIG. 5. For example, only one core is employed in association with the 1 key, the secondary winding thereof being in circuit with the 1 binary line 53. Likewise, only one core is used in association with the 2 key, its secondary winding being in circuit with the 2 line 53, etc.

It will be seen that the arrangement of the cores relative to the keys is in accordance with the conventional 1, 2, 4 and 8 system of binary notation so that a particular single one or combination of the flip-flop circuits 30 will be set according to the particular key depressed.

In operation, the flip-flop circuits are reset by applying a suitable pulse over a resetting line 34 connected to each flip-flop circuit.

Obviously, the depressed key may be held depressed for any period of time Without effecting the setting of the associated flip-flop circuit or circuits as long as the latter are not reset by application of a pulse over line 34. Also, any number of pulses can be fed over circuit 32 during depression of any key without erroneously affecting the setting of the circuits 30.

In the modification shown in FIGS. 6 and 7, the cores 25a associated with each key are embedded in a block of plastic 34 aligned with the respective key and'mounted in an opening formed in the base plate 35. A permanent magnet 36 is also embedded in the block 34 in direct proximity to the cores 25a and with its magnetic axis extending vertically. Thus, the cores are normally fully saturated as long as the key is in raised position.

A second permanent magnet 37 is suitably attached to the bottom of the key stem 38 of the respective key and is located with its magnetic axis extending coincident with the axis of the magnet 36. Also, the magnet 37 is located with the polarity thereof extending opposite to the polarity of the magnet 36.

The various keys and their magnets 37 are normally spring held in their upper illustrated positions wherein the magnets 37 have no effect on the magnets 36. Therefore, each magnet 36 is effective to normally magnetically saturate its associated cores to prevent generation of pulses in the secondary windings thereof. However, upon depression of any key, its magnet 37 will be moved into close proximity with the associated magnet 36, thereby neutralizing the magnetic fiux of the latter to such an extent that the associated cores will become unsaturated sufliciently to enable generation of pulses in the secondary windings thereof by the usual transformer action of the cores.

FIGS. 8 and 9 illustrate a further modified form of the invention in which the cores 25b associated with the different keys are normally unsaturated. The various cores are mounted in blocks 40 of plastic located directly below the respective keys. Permanent magnets 41 having their magnetic axes extending vertically are suitably secured to the lower ends of the key stems 42 of assoicated keys. Normally, when the keys are in their normal illustrated raised positions, the magnets 41 are removed sufficiently from the cores 25a to prevent saturation thereof. Upon depression of a key, however, its magnet 41 will be moved to such close proximity with the associated cores as to 4 completely saturate the same and thus prevent generation of pulses in their secondary windings.

The cores associated with the keys of FIG. 8 are located, as shown in FIG. 9, in a manner somewhat similar to the arrangement shown in FIG. 5. That is, four binary lines 57 having the values 1, 2, 4 and 8 assigned thereto, are connected in series with the secondary windings of certain associated cores and with the input of respective flip-flop circuits 3011. Likewise, a pulse line 32a connected to a pulse generator 33a is located in series with the primary windings of all cores.

However, the phase relationship between the primary and secondary windings on alternate ones of the cores associated with any one binary line, i.e. l, 2, 4, 8, is in opposition with the phase relationship between the primary and secondary windings of the remaining ones of the cores associated with the respective binary lines. This is indicated by the reversed wiring condition 43 for all alternate cores. Further, an even number of cores and windings are provided for each binary line and where such is normally not the case, as in connection with the 1 binary line in the particular pattern shown in FIG. 9, an additional core 44 with its associate primary and secondary winding is provided. Thus, a balanced condition is provided for all four binary lines.

When no key is depressed and pulses or current changes are applied over circuit 32a by the pulse generator 33a, pulses of equal but opposite polarity will be generated in the successive secondary windings in any one line. Therefore, each pulse generated in a secondary winding will be cancelled out by the pulse of opposite polarity generated by the secondary winding of the next succeeding core.

When any amount key is depressed to accordingly saturate its associated core or cores 25b, a pulse will not be generated in the respective secondary winding and, therefore, the pulse from the preceding winding will not be cancelled out and accordingly will be transferred along the respective binary line to set its flip-flop circuit.

After setting appropriate flip-flop circuits 30a by depression of any key and utilizing the information set up thereon, the latter are reset by application of a suitable pulse over a reset line 34a connected to all such circuits.

FIG. 10 illustrates a bi-stable multi-vibrator or flipflop circuit which may be utilized to set up representation of the binary information received over a binary line of either of the circuits shown in FIGS. 5 and 9. The circuit includes two grounded emitter transistors 45 and 46. The collector of each transistor is connected to the base of the other by a resistor 47 of 10,000 ohms bridged by a condenser 48 of .01 mfd. The collectors of the transistors 45 and 46 are also connected through resistors 50 and 51, respectively, of 500 ohms each to a positive potential supply line 52.

The respective binary line 53, is connected through a transformer 54 and coupling condenser 55 to the base of the transistor 45. On the other hand, the reset line 34 is connected through a coupling condenser 56 to the base of transistor 46.

Assuming the circuit conditions to be such that the transistor 46 is in conducting condition, the voltage drop across the resistor 51 is applied across resistor 47 and condenser 48 to reduce the bias current in transistor 45, holding the latter in cut-off condition and thus maintaining the circuit in a stable unset condition. Upon an application of a pulse, as described heretofore, over the respective binary line 53 and through the transformer 54 and condenser 55 to the base of transistor 45, the current bias therein is increased, causing transistor 45 to conduct. Accordingly, the increased voltage drop across resistor 50 is applied to transistor 46, reducing the bias current in the latter to cause the same to become nonconducting and thus leaving the circuit in a stable set condition. Subsequent application of a reset pulse over the line 34 will again increase the current bias in transistor 46 to cause the same to conduct and reverse the circuit back to its original unset condition.

Although I have described my invention in detail in its preferred embodiment and modified embodiments and therefore have utilized certain specific terms and languages herein, it is to be understood that the present disclosure is illustrative, rather than restrictive and that changes and modifications may be resorted to without departing from the spirit or scope of the claims appended hereto.

Having thus described the invention, What I desire to secure by United States Letters Patent is:

1. In a keyboard unit, the combination comprising a plurality of manually operable keys, a plurality of circuit control devices associated with said keys, each of said control devices including a primary winding, a secondary winding, and magnetic coupling means cooperating with said windings whereby to enable a current change in said primary winding to generate a pulse in said secondary winding; a plurality of pulse utilization devices, circuit means connecting the secondary windings of certain of said control devices to one of said pulse utilization devices, circuit means connecting the secondary windings of others of said control devices to another of said pulse utilization devices, means for applying a current change to the primary windings of all of said control devices, magnetic means associated with each of said keys for normally magnetically saturating the coupling means associated with the respective key, and a magnetic shield operable by said last mentioned key for disabling the magnetic saturation of the magnetic coupling means associated with said last mentioned key.

2. In a keyboard unit, the combination comprising a plurality of manually depressible keys having key stems of magnetically shieldable material, a plurality of circuit control devices associated with said keys, each of said control devices including a core of magnetic material, and primary and secondary windings on said core arranged to enable a current change in said primary winding to generate a pulse in said secondary winding; a plurality of pulse utilization devices, circuit means connecting the secondary windings of certain of said control devices to one of said pulse utilization devices, circuit means connecting the secondary windings of others of said control devices to another of said pulse utilization devices, means for applying a current change to the primary windings of all said control devices, and a permanent magnet adjacent each core and effective to magnetically saturate the same, the key stem of any depressed one of said keys being positioned intermediate the magnet and the core or cores associated with said depressed key whereby to disable said magnetic saturation of said last mentioned core or cores.

3. In a keyboard unit, the combination comprising a plurality of manually depressible keys, a plurality of circuit control devices associated with said keys, each of said control devices including a core of magnetic material and primary and secondary windings on said core arranged to enable a current change in said primary winding to generate a pulse in said secondary winding; a plurality of pulse utilization devices, circuit means connecting certain of said secondary windings to one of said pulse utilization devices, circuit means connecting certain others of said secondary windings to another of said pulse utilization devices, means for applying a current change to all of said primary windings, first permanent magnets located in proximity with said cores whereby to normally magnetically saturate said cores, and second permanent magnets carried by said keys, each of said second magnets being effective upon depression of its respective key to neutralize the magnetic effect of one of said first magnets.

4. In a keyboard unit, the combination comprising a plurality of depressible amount keys, one or more control devices associated with each of said keys, each of said control devices including a toroidal core of magnetic material, and primary and secondary windings on said core arranged to enable a current change in said primary winding to generate a pulse in said secondary winding; said control devices associated with any one of said keys being embedded in a support element of insulating material, means for maintaining said support elements in cooperative relation with respective ones of said keys, each of said control devices having assigned thereto a binary value, said control devices being associated with said keys in accordance with the binary equivalent of decimal numerical values assigned to said keys, a plurality of pulse utilization devices, circuit means connecting the secondary windings of all like valued ones of said control devices to respective ones of said pulse utilization devices, magnetic means normally magnetically saturating said cores, means for simultaneously applying a current change to all of said primary windings, and magnetic elements canied by said keys and effective upon depression thereof for disabling magnetic saturation of the control devices associated with the respective depressed key.

5. In a keyboard unit, the combination comprising a plurality of manually depressible keys, a plurality of circuit control devices associated with said keys, each of said control devices including a core of magnetic material, and primary and secondary windings on said core arranged to enable a current change in said primary winding to generate a pulse in said secondary winding; each of said control devices having assigned thereto a binary value, said control devices being associated with said keys in accordance with a binary equivalent of decimal numerical values assigned to said keys, a plurality of pulse utilization devices, circuit means connecting the secondary windings of all like valued ones of said control devices in series with each other and with respective ones of said pulse utilization devices, the primary and secondary windings of all alternate like valued ones of said control devices being arranged in opposite phase relation to the primary and secondary windings of all remaining like valued ones of said control devices whereby to normally prevent generation of a pulse in any of said circuit means, means for simultaneously applying a current change to all of said primary windings, and magnetic elements operable by respective ones of said keys and each effective upon depression of its respective key to magnetically saturate the core or cores of the said control device or devices associated with said depressed key whereby to generate a pulse in respective ones of said circuit means.

6. In a keyboard unt, the combination comprising a plurality of selectively operable elements, a plurality of circuit control devices associated with respective ones of said elements, each of said control devices including a core of magnetic material, and primary and secondary windings on said core arranged to enable a current change in said primary winding to generate a pulse in said secondary winding; a plurality of pulse utilization devices, circuit means connecting the secondary windings of certain of said control devices in series with each other and with one of said pulse utilization devices, circuit means connecting the secondary windings of others of said control devices in series with each other and with another of said pulse utilization devices, means for applying a current change to all of said primary windings, the primary and secondary windings of all alternate ones of said control devices whose secondary windings are connected in series being arranged in opposite phase relation to the primary and secondary windings of all remaining controlled devices whose secondary windings are connected in series with the secondary windings of said alternate control devices whereby to normally prevent generation of a pulse in any of said circuit means, and means operable by any selected one of said ele- References Cited in the file of this patent UNITED STATES PATENTS Keister Aug. 8, 1950 Bruns Oct. 17, 1950 8 Bowyer Aug. 4, 1953 Quinby et a1. Nov. 17, 1953 Chen Jan. 31, 1956 Burkhart Feb. 14, 1956 Booth Feb. 28, 1956 Tnimble Mar. 27, 1956 Saunders Feb. 12, 1957 Davis Nov. 19, 1957 

